Light-producing beetles are the most diverse bioluminescent land animals . Like fireflies, the 99-million-year-old Cretophengodes azari beetle would use light to protect itself from predators or to attract potential mates. Fortunately, amber has allowed the light organ in her abdomen to be intact.
The evolution of bioluminescence in these beetles is associated with unusual morphological modifications, such as soft body and neoteny (retardation or slowing of physiological development), but the fragmentary nature of their fossil record reveals little about the origin of these adaptations.
“Most light-producing beetles are soft-bodied and quite small, so they have little fossil record,” says Chenyang Cai, a researcher at the University of Bristol School of Earth Sciences and the Institute of Geology. and Nanjing Paleontology. “However, the new fossil, found in amber from northern Myanmar, is exceptionally well preserved, even the organ of light in its abdomen is intact.”
The ancient beetle is so unique that scientists have created a new family for it : Cretophengodidae.
“The discovery of a new family of extinct elateroid beetles is significant because it helps shed light on the evolution of these fascinating beetles,” the authors continue.
“The newly discovered fossil represents an extinct relative of fireflies and the living families Rhagophthalmidae and Phengodidae, “ explains Yan-Da Li, a researcher at Peking University, who co-authored the work. “We believe that light production initially evolved in the soft, vulnerable larvae of the beetle as a defensive mechanism to protect themselves from predators.”
Thus, it is clear that the fossil shows that during the Cretaceous period, adult beetles also had bioluminescence.
Referencia: Yan-Da Li et al. 2021. Cretophengodidae, a new Cretaceous beetle family, sheds light on the evolution of bioluminescence. Proc. R. Soc. B 288 (1943): 20202730; doi: 10.1098/rspb.2020.2730
